Heat exchange mill

ABSTRACT

In a heat exchange and blending device for heat exchange treatment of flowable materials, comprising a tumbling mill including a normally closed casing having a pair of tube sheets disposed in parallel relation transversely of the said casing and subdividing the casing into a generally cylindrical tube section and generally conical mixing chamber end sections at opposite ends thereof; generally parallel tubes extending endwise between the tube sheets in open communication with the end sections; means to pass heat exchange fluid through the tube section for contact with the outer surfaces of tubes therein; and means mounting the casing for rotation of the tube and end sections in unison about an axis transverse to the lengthwise direction of the tubes to effect movement of a load of material alternately from one end section through the tubes into the other end section, the improvement including the provision of at least one apertured baffle plate arranged parallel to the tube sheets and cooperating therewith to divide the casing tube section into heat exchange fluid inlet and outlet reservoirs interconnected solely by a plurality of orifices defined by the baffle plate apertures and the outer surfaces of the tubes extending therethrough. Vapor pressure control within the mixing chambers is effected by a system including filtering units accessible from exteriorly of the mixing chambers.

United States Patent ABSTRACT: In a heatexchange and blending device for heat sections at opposite ends thereof; generally parallel tubes extending endwise between the tube sheets in open communication with the end sections; means to pass heat exchange fluid through the tube section for contact with the outer surfaces of tubes therein; and means mounting the casing for rotation of the tube and end sections in unison about an axis transverse to the lengthwise direction of the tubes to effect movement of a load of material alternately from one end section through the tubes into the other end section, the improvement including the provision of at least one apertured baffle plate arranged parallel to the tube sheets and cooperating therewith to divide the casing tube section into heat exchange fluid inlet and outlet reservoirs interconnected solely by a plurality of orifices defined by the baffle plate apertures and the outer surfaces of the tubes extending therethrough. Vapor pressure control within the mixing chambers is effected by a system including filtering units accessible from exteriorly of the mixing chambers. v

ROOM THERMOSTAT' [72] Inventor John J. Fischer East Stroudsburg, Pa. [21] Appl. No. 25,098 [22] Filed Apr. 2, 1970 [45] Patented Aug. 17, 1971 [73] Assignee The Patterson-Kelley Co., Inc.

" East Stroudsburg, Pa.

[54] HEAT EXCHANGE-MILL 9 Claims, 7 Drawing Figs.

[52] U.S. Cl 165/86, 34/92 [51] 1nt.Cl ..F28d 11/00, F 28f 5/00 [50] Field of Search, 165/86; 34/15, 92

[56] References Cited UNITED STATES PATENTS 2,919,116 12/1959 Fischer 165/86 Primary ExaminerCarroll B. Dority, Jr. Attorney-Bean & Bean N um'r ill? 'Fuil. VALVE BLOWE R JUNCTION MOTOR BOX PATENTED AUG] 7 I971 SHEET 1 0F 4 INVENTOR.

JOHN J. FISCHER ATTORNEYS PATENTEDAUEWIQYI $599,709

SHEET 2 BF 4 JOHN J. FISCHER I 5 BY 6% @mu ATTORNEYS PATENTED AUG] 7 I97! SHEET 3 OF 4 INVENTOR.

JOHN J. FISCHER @aw @QM A TTORNEYS PATENTED AUG] 7 I97| INVENTOR.

JOHN J. FISCHER A T TORNEYS HEAT EXCHANGE MILL BACKGROUND OF THE INVENTION In my prior US. Pat. No. 2,9l9,l 16, there is disclosed a tubular vacuum dryer including a normally closed casing having a pair of tube sheets disposed in parallel relation transversely of the casing and subdividing the easing into a generally cylindrical tube section and generally conical mixing chamber end sections at opposite ends thereof; generally parallel tubes extending endwise between the tube sheets in open communication with the end sections; means mounting the casing for rotation of the tube section and the end sections in unison about an axis transverse to the lengthwise direction of the tubes, such that upon rotation of the casing a load of material therein slides alternately from one end section through the tubes into the other end section, and vice versa; and means for circulating a heat exchange fluid through the casing tube section in heat exchange contact with the external surfaces of the tubes.

SUMMARY OF-TI-IE INVENTION The present invention relates to improvements in vacuum dryers of the type disclosed by my prior US. Pat. No. 2,919,1 16.

A particularly important feature of the present invention is to provide one or more baffle plates, arranged parallel to the tube sheets and cooperating therewith to divide the casing tube section into heat exchange fluid inlet and outlet sections interconnected solely by a plurality of annularly shaped orifices defined by the baffle plate apertures and the outer surfaces of the tubes extending through the apertures.

Preferably, two such baffle plates are provided so as to additionally define a chamber therebetween in which all heat exchange fluid passing between the reservoirs flows parallel to the axes of the respective tubes along a substantial length thereof. The flow of fluid may be visualized as ideally being in the form of cylindrical flows bounding each tube. This arrangement not only substantially increases heat exchange efficiently over that obtainable by passing heat exchange fluid transversely of or randomly about the tubes, but ensures that all of the tubes will be maintained at substantially the same temperature throughout a substantial portion of their lengths.

In the above construction, it has been foundto be particularly important to provide a substantially perfect seal between the peripheral edges of the baffle plates and the inner wall of the casing, since extraneous flow paths would otherwise be set up with the result that heat exchange efficiency may be reduced to below that obtainable from conventional flow without baffle plates.

The invention additionally includes a novel dryer vacuum system including a conduit, which extends through the tube section and terminates adjacent opposite ends thereof in filter devices arranged in the mixing chambers, but accessible exteriorly of the casing.

DRAWINGS The nature and mode of the present invention will be more fully described in the following detailed description taken with the accompanying drawings, wherein:

FIG. I is an elevational view, partially in section showing the mill of the present invention;

FIG. 2 is an end elevational view of the mill of FIG. 1;

FIG. 3 is a sectional view taken generally along the line 3-3 in FIG. 1;

FIG. 4 is an enlarged fragmentary view of that portion of the mill designated as 4 in FIG. 1;

FIG. 4a is an enlarged fragmentary view of the area designated as FIG. 4a in FIG. 4;

FIG. 5 is an enlarged fragmentary view of that portion of the dryer designated as 5 in FIG. 1; and

FIG. 6 is an enlarged fragmentary view of that portion of the dryer designated as 6 in FIG. 1.

DETAILED DESCRIPTION Now referring particularly to FIG. 1, a tumbling mill or vacuum dryer embodying the features of the present invention is generally designated as 1. Mill 1 includes a casing 2 formed with a generally tubular-shaped central wall portion 10 and a pair of frustoconical-shaped end wall portions 12, 14 having material inlet and discharge ports normally covered by closures 16, 18, respectively.

Casing 2 is fitted interiorly with header plates 2022, which are bored in mutual alignment to receive therebetween a plurality of heat exchange tubes 25, as in the manner of conventional steam boiler constructions. Thus, it will be appreciated from viewing FIG. 1 that the headers 2022 subdivide the interior of the casing 2 into a tube or central section 10a, which is generally bounded by wall portion 10; and a pair of conically shaped mixing chambers or end sections 12a, 14a, which are generally bounded by wall portions l2, l4 and interconnected by material flow passageways defined by tubes 25.

Casing 2 is rotatably mounted by means of stub shafts 26, 28 running within bearings 29 carried by pedestals 30-30, as best shown in FIGS. 1, 4 and 6. Suitable means, such as electric motor 32 and gear train 33, 34, shown in FIGS. 1 and 2, may be employed to effect rotation of the casing about the axis defined by shafts 26, 28 for the reason to be hereinafter discussed.

In accordance with the present invention, heat exchange fluid is circulated in contact with the outer surfaces of tubes 25 by means of a circulation system, which is shown in FIGS. 1 and 6 as generally including inlet and outlet conduits 36, 38; fluid connections defined by rotary union device 39 (FIG. 6); a centrally hollowed portion of the stub shaft 26; and fluid inlet and outlet tubes 40, 42 arranged interiorly of tube section 10a. Suitable means, not shown, may be employed to draw or force heat exchange fluid, such as hot or cold water, through the circulation system for the purpose of maintaining tubes at a desired process temperature.

It is a particular feature of the present invention that tube section 10a is subdivided by at least one and preferably two fluid flow control baffle plates 44, 46 which are arranged in a parallel, spaced relationship to headers 20, 22, so as to define inlet and outlet reservoirs 44a, 46a with which tubes 40, 42 are in fluid communication, respectively. When two baffle plates are provided, they cooperate to define an intermediate chamber 47 through which heat exchange fluid moves in passing between reservoirs 44a, 46a. Baffle plates 44, 46 are fluid sealed about their peripheral edges relative to wall portion 10, as by welding, and are provided with a plurality of apertures 48, whose configurations preferably correspond to the external configurations of the tubes 25 which pass therethrough. Apertures 48 are best shown in FIGS. 3, 4 and 4a as being sized larger than tubes 25, so as to define therewith orifices 48a through which heat exchange fluid is forced to flow in order to circulate across the baffle plates between inlet tube 40 and outlet tube 42. When tubes 25 are of circular configuration, apertures 48 are preferably arranged concentrically thereof such that orifices 48a are of annular configuration and heat exchange fluid passing between reservoirs 44a, 46a is constrained to flow axially of tubes 25 in immediate contact with the entire peripheral surface thereof, so as to maintain a highly efficient heat exchange scrubbing action. When as is preferred, two baffle plates are provided, heat exchange fluid passing through chamber 47 follows cylindrical flow paths immediately bounding each tube and thereby ensures that all of the tubes are maintained at substantially the same temperature through a substantial portion of their lengths. As a result, material being processed in uniformly heated or cooled within tube section 10a, and the process may be more accurately controlled.

A change of material to be processed, such as indicated at 35 in FIG. 1, may be placed within casing 2, when it has been rotated so as to position the inlet port of mixing chamber 12a in its uppermost position, also shown at FIG. 1, and cover 16 removed. After closing of the cover 16, casing 2 is rotated under the control of motor 32, with the result that charge 35 will be alternately transferred back and forth between the mixing chambers 12a, 14a through the tubes 25. Rotation of casing 2 results in the remixing or blending of the charge within the mixing chambers of the casing, as well as heat exchange scrubbing movements thereof within tubes 25.

Mill 1 also features a vapor pressure control arrangement whereby the ambient pressure acting upon the charge of material being processed is regulated to provide optimum processing conditions. For example, if the processing involves an exothermic chemical reaction, and if the materials in process are propense to quality degradation under certain temperature conditions, the requisite material drying and reaction processes (without quality degradation) may be readily attained in the mill by suitable regulation of the absolute pressure of the vapor environment within the mixing chambers. In similar fashion, in processes involving diffusional drying" (for example, in the drying of Nylon materials) the operative pressure, as well as the temperature, of the environment within the processing vessel are most critical factors.

To accommodate these operational prerequisites, and to obtain improved operational efficiencies, mill 1 embodies an improved vapor pressure control system, which is illustrated primarily in FIGS. 1, 4 and as including a conduit 50 mounted within a hollow interior portion of the stub shaft 28 in axial alignment with a relatively stationary exit conduit 52, which in turn'is connected to a suitable vacuum (or pressure) supply device orvsource, not shown. A suitable packing gland or seal device 53 is employed to provide a fluid seal between adjacentfends of conduits 50, 52.

The inner end of the conduit 50 is arranged in fluid communication with the interior of a standpipe 54, which extends through the headers 20, 22 and baffle plates 44, 46 in fluidsealed relation therewith. Opposite ends of standpipe 54 are disposed in fluid communication with the interiors ofa pair of identical, cylindrical-shaped filter units 55, and thus in fluid communication with the interiors of mixing chambers 12a, 14a, in which units 55 are arranged.

As shown in detail at FIG. 5, each of the filter units 55 comprises a metal cylinder 56, which isperforated as at 57 and enclosed within concentrically arranged screenSS and an outer fluid-permeable wrapper 60 formed of felted Dacron fibers, or the like. In the arrangement illustrated, cylinder 56 is welded, as indicated at 62, to dependent annular flange 63 of cover plate 64, which is in turn adapted to be detachably mounted, as by bolts 65, to annular flange 66 carried one on each of wall portions 12 and 14. By referring to FIG. 1, it will be understood that flanges 66 bound filter access openings disposed in substantial alignment with the opposite open ends of standpipe 54. Screen 58 is slideably received in cylinder 56 and maintained in position thereon by an inwardly tapered annular fitting 68, which is in turn removably supported relative to annular flange 63 by straps 70, 72 which clampingly secure wrapper 60 to both of flange 63 and fitting 68. Suitable means, such as O-ring seals 74, may be employed to fluid seal fittings 68 relative to the end ofstandpipe 54 and cover plates 64 relative to flange 66. Thus, it will be apparent that filters unit 55 are easily removed from mixing chambers 12a, 14a by merely removing cover plates 64 and thereafter disassembled for maintenance purposes by the removal of straps 70, 72. To reinstall units 55, it is only necessary to mount cover plates 65 on flanges 66, since tapered fitting 68 function to automatically align and seal the units about the open ends of standpipe Alternatively, filtering units 55 may be formed separately from cover plates 65; the latter serving merely to afford access to the filter units or to clamp same in place relative to the ends of standpipe 54.

I claim:

1. In a heat exchange and blending mill for heat exchange treatment of flowable materials, comprising a normally closed casing having a pair of tube sheets disposed in parallel relation transversely of said casing and subdividing said casing into a generally cylindrical tube section and generally conical mixing chamber end sections at opposite ends thereof; generally parallel tubes extending endwise between said tube sheets in open communication with said end sections; means to pass heat exchange fluid through said tube section for contact with outer surfaces of said tubes; and means mounting said casing for rotation of said tube and end sections in unison about an axis transverse to the lengthwise direction of said tubes to effect movementof material alternately from one said end section through said tubes into the other said end section, the improvement including:

at least one baffle plate fluid-sealed peripherally thereof to said casing and arranged parallel to said tube sheets, said baffle plate and tube sheets dividing said tube section into heat exchange fluid inlet and outlet reservoirs, said baffle plate having apertures to receive said tubes for passage therethrough, said reservoirs being interconnected through said baffle plate solely by a plurality of orifices defined by said baffle plate apertures and the outer surfaces of said tubes extending therethrough.

2. The improvement according to claim 1, wherein said tubes and said apertures are substantially circular in section.

3. The improvement according to claim 2, wherein said apertures are disposed substantially concentrically of said tubes such as to define therewith orifices of annularly shaped configuration.

4. The improvement according to claim 1, wherein two baffle plates are arranged parallel to said tube sheets, one of said plates cooperating with one of said sheets to define said inlet reservoir and another of said plates cooperating with another of said sheets to define said outlet reservoir, said plates cooperating with each other to define an intermediate chamber connected solely'to said reservoirs by said orifices, whereby heat exchange fluid passing between said reservoirs is constrained to pass lengthwise of said tubes in heat exchange relation with the outer surfaces thereof.

5. The improvement according to claim 4, wherein said tubes and apertures are substantially circular in section, and said apertures are disposed substantially concentrically of said tubes.

6. A heat exchange and blending mill for heat exchange treatment of flowable materials, comprising in combination:

a normally closed casing having a pair of tube sheets disposed in parallel relation transversely of said casing and subdividing said easing into a generally cylindrical tube section and generally conical mixing chamber end sections at opposite ends thereof;

generally parallel tubes extending endwise between said tube sheets in open communication with said end sectrons;

means to pass heat exchange fluid through said tube section for contact with outer surfaces of said tubes;

means mounting said casing for rotation of said tube and end sections in unison about an axis transverse to the lengthwise direction of said tubes to effect movement of material alternately from one said end section through said tubes and into the other said end section;

means for connecting at least one of said end sections with vapor pressure control means arranged exteriorly of said casing, said connecting means including conduit means extending inwardly of said tube section and terminating in at least one end portion opening through one of said tube sheets into said one end section and a filter unit arranged within said one end section and having one end thereof removably engageable with said one end portion;

means defining an access opening in said casing bounding said one end section, said access opening being disposed substantially in alignment with said one end portion and sized to permit removal of said filter unit outwardly therethrough;

and a cover device removably mounted on said access-' opening-defining means, said cover device when mounted closing said access opening and maintaining said filter unit in engagement with said one end portion.

7. The mill according to claim 6, wherein another end of said filter device is fixed to said cover device, such that said filter is automatically positioned in engagement with said one end portion when said cover device is mounted.

8. The improvement according to claim 6, wherein said means to pass heat exchange fluid through said tube section includes two baffle plates fluid-sealed peripherally thereof to said casing and arranged parallel to said tube sheets, one of said plates cooperating with one of said sheets to define a heat exchange fluid inlet reservoir and another of said plates cooperating with another of said sheets to define a heat exchange fluid outlet reservoir, said plates cooperating with each other to define an intermediate chamber, said plates having apertures to receive said tubes for passage therethrough, said apertures being sized larger than said tubes and cooperating with the outer surfaces thereof to define orifices, said reservoirs being connected to said intemiediate chamber solely by said orifices, whereby heat exchange fluid passing through said intermediate chamber between said reservoirs is constrained to pass lengthwise of said tubes in heat exchange relation with the outersurfaces thereof.

9. The improvement according to claim 8, wherein said tubes and apertures are substantially circular in section, and said apertures are disposed substantially concentrically of said tubes. 

1. In a heat exchange and blending mill for heat exchange treatment of flowable materials, comprising a normally closed casing having a pair of tube sheets disposed in parallel relation transversely of said casing and subdividing said casing into a generally cylindrical tube section and generally conical mixing chamber end sections at opposite ends thereof; generally parallel tubes extending endwise between said tube sheets in open communication with said end sections; means to pass heat exchange fluid through said tube section for contact with outer surfaces of said tubes; and means mounting said casing for rotation of said tube and end sections in unison about an axis transverse to the lengthwise direction of said tubes to effect movement of material alternately from one said end section through said tubes into the other said end section, the improvement including: at least one baffle plate fluid-sealed peripherally thereof to said casing and arranged parallel to said tube sheets, said baffle plate and tube sheets dividing said tube section into heat exchange fluid inlet and outlet reservoirs, said baffle plate having apertures to receive said tubes for passage therethrough, said reservoirs being interconnected through said baffle plate solely by a plurality of orifices defined by said baffle plate apertures and the outer surfaces of said tubes extending therethrough.
 2. The improvement according to claim 1, wherein said tubes and said apertures are substantially circular in section.
 3. The improvement according to claim 2, wherein said apertures are disposed substantially concentrically of said tubes such as to define therewith orifices of annularly shaped configuration.
 4. The improvement according to claim 1, wherein two baffle plates are arranged parallel to said tube sheets, one of said plates cooperating with one of said sheets to define said inlet reservoir and another of said plates cooperating with another of said sheets to define said outlet reservoir, said plates cooperating with each other to define aN intermediate chamber connected solely to said reservoirs by said orifices, whereby heat exchange fluid passing between said reservoirs is constrained to pass lengthwise of said tubes in heat exchange relation with the outer surfaces thereof.
 5. The improvement according to claim 4, wherein said tubes and apertures are substantially circular in section, and said apertures are disposed substantially concentrically of said tubes.
 6. A heat exchange and blending mill for heat exchange treatment of flowable materials, comprising in combination: a normally closed casing having a pair of tube sheets disposed in parallel relation transversely of said casing and subdividing said casing into a generally cylindrical tube section and generally conical mixing chamber end sections at opposite ends thereof; generally parallel tubes extending endwise between said tube sheets in open communication with said end sections; means to pass heat exchange fluid through said tube section for contact with outer surfaces of said tubes; means mounting said casing for rotation of said tube and end sections in unison about an axis transverse to the lengthwise direction of said tubes to effect movement of material alternately from one said end section through said tubes and into the other said end section; means for connecting at least one of said end sections with vapor pressure control means arranged exteriorly of said casing, said connecting means including conduit means extending inwardly of said tube section and terminating in at least one end portion opening through one of said tube sheets into said one end section and a filter unit arranged within said one end section and having one end thereof removably engageable with said one end portion; means defining an access opening in said casing bounding said one end section, said access opening being disposed substantially in alignment with said one end portion and sized to permit removal of said filter unit outwardly therethrough; and a cover device removably mounted on said access-opening-defining means, said cover device when mounted closing said access opening and maintaining said filter unit in engagement with said one end portion.
 7. The mill according to claim 6, wherein another end of said filter device is fixed to said cover device, such that said filter is automatically positioned in engagement with said one end portion when said cover device is mounted.
 8. The improvement according to claim 6, wherein said means to pass heat exchange fluid through said tube section includes two baffle plates fluid-sealed peripherally thereof to said casing and arranged parallel to said tube sheets, one of said plates cooperating with one of said sheets to define a heat exchange fluid inlet reservoir and another of said plates cooperating with another of said sheets to define a heat exchange fluid outlet reservoir, said plates cooperating with each other to define an intermediate chamber, said plates having apertures to receive said tubes for passage therethrough, said apertures being sized larger than said tubes and cooperating with the outer surfaces thereof to define orifices, said reservoirs being connected to said intermediate chamber solely by said orifices, whereby heat exchange fluid passing through said intermediate chamber between said reservoirs is constrained to pass lengthwise of said tubes in heat exchange relation with the outer surfaces thereof.
 9. The improvement according to claim 8, wherein said tubes and apertures are substantially circular in section, and said apertures are disposed substantially concentrically of said tubes. 